Automatic Balancing Centrifugal Apparatus By Fluid Compsensation

ABSTRACT

The invention relates to an automatic balancing centrifugal apparatus by fluid compensation, which compensates a load imbalance among buckets holding samples by injecting a fluid into the buckets or sucking the fluid from the buckets, thereby simplifying the overall structure of the centrifugal apparatus, increasing the durability, and centrifuging a large quantity of samples under various high-speed rotation conditions smoothly. The automatic balancing centrifugal apparatus by fluid compensation comprises: rotors on which a plurality of buckets are mounted; a centrifuge motor for rotating said rotors; a load measurement mechanism, which is installed so as to lift and lower along the rotation trace of said buckets and which measures the load of said buckets while the restraint of the buckets is being released at the time of lifting; a position sensing mechanism for sensing whether or not each of said buckets is positioned right above said load measurement mechanism; a fluid compensation mechanism for injecting a fluid into said buckets or for sucking the fluid from the buckets; and a main control part for controlling the overall operations of each of said elements and for controlling said fluid compensation mechanism so that the loads of said buckets can become equal to each other.

TECHNICAL FIELD

The invention relates to an automatic balancing centrifugal apparatus byfluid compensation, and particularly to an automatic balancingcentrifugal apparatus by fluid compensation which is capable ofcompensating a load unbalance among buckets holding samples by injectinga fluid into the buckets or sucking the fluid from the buckets.

BACKGROUND ART

A centrifugal apparatus is one which rotates rotors holding samples athigh speed to apply a large centrifugal acceleration to the samples, sothat high-density sample components can be placed on an outer layer in aradial direction and low-density sample components can be placed on aninner layer in a radial direction to separate the components from eachother. An automatic balancing centrifugal apparatus is one, whichcalculates load differentials of each bucket, which inevitably occur dueto the number of samples or the load differentials of each sample heldin each bucket, and the like, and automatically maintains a balancebefore centrifugation.

FIG. 1 is a schematic perspective view of a conventional automaticbalancing centrifugal apparatus by lever movement. As shown in FIG. 1,the conventional automatic balancing centrifugal apparatus by levermovement comprises a centrifuge motor (2); a rotor (20) which is axiallybonded to the centrifuge motor (2) to be rotated; a rotor lever (22)which rotates while supporting buckets (40) and is supported so as to becapable of being horizontally moved with respect to the rotor (20); anelevator-type load measurement mechanism (hereinafter “load measurementmechanism”) which measures the loads of both buckets (40) beforecentrifugation in order to sense the load unbalance of both buckets(40); a slip ring (50) which is fixed in a given place to a centrifugemotor shaft (4) and extends from the power lines and signal lines ofelectrical/electronic components within the rotor (20) to be exposed tothe outside; and a wiring terminal carrier (60) which extends from theexternal power lines and signal lines and mounts a wiring terminal (notshown) disposed in one-to-one correspondence with the slip ring (50) tocontact and separate with respect to the slip ring (50). Referencenumeral 22A indicates bucket support arms formed on the rotor lever(22), and reference numeral 42 indicates a locking groove which isformed on the bucket (40) and is locked in the bucket support arms(22A). Meanwhile, the conventional automatic balancing centrifugalapparatus by lever movement may further comprise a position sensor (notshown) for positioning the bucket (40) right above the load measurementmechanism (30).

In the above-described constitution, an operator lifts a loading plateof the load measurement mechanism (30) before each centrifugation whilepositioning one bucket (40) right above the load measurement mechanism(30). Then, the operator measures the load of the bucket (40) while thebucket (40) is released with respect to the rotor lever (22), and theoperator lowers the loading plate and measures the load of anotherbucket (40) in the same manner, thereby measuring a load differentialbetween both buckets (40). Thereafter, in order to keep a dynamicbalance among samples in the buckets (40) at the time of rotation forcentrifugation, a lever carrying motor (not shown) mounted within therotor (20) is driven to thereby adjust a differential in distancebetween the bucket (40) and the rotor rotation shaft which correspondsto the load differential of the buckets (40), thereby making centrifugalforces applied to the samples at both ends uniform. To do this, thewiring terminal carrier (60) is moved forward to supply required powerand control signals to the lever carrying motor while being in contactwith the slip ring (50). Then, the wiring terminal carrier (60) is movedbackward to be separated from the slip ring (50). The overallconstitution or individual constitutions of the automatic balancingcentrifugal apparatus by lever movement are specifically disclosed inKorean Patent No. 343336, entitled “Automatic balance adjustingcentrifuge apparatus”; Korean Patent Application No. 2002-17498,entitled “Automatic balance adjusting centrifuge apparatus”; KoreanPatent Application No. 2004-26526, entitled “Elevator-type loadmeasurement apparatus”; Korean Patent Application No. 2004-76489,entitled “Automatic balancing rotor for centrifuges”; and Korean PatentApplication No. 2004-76490, entitled “Signal transfer apparatus of arotating body,” filed by the same applicant, and the explanationsthereof in detail will be omitted here. All patents and patentapplications mentioned herein are incorporated herein by reference.

However, the above-described conventional automatic balancingcentrifugal apparatus by lever movement needs a very precise levercarrying mechanism as well as a slip ring being a non-contact electricalconnection and an external wiring terminal carrying mechanism in orderto supply power or signals to the lever transfer motor. Due to suchcomplex mechanism and electrical characteristics, the conventionalautomatic balancing centrifugal apparatus by lever movement has alimited durability compared to a typical centrifugal apparatus withoutautomatic balancing function; there is a limit in processing a largequantity of samples due to a limited bucket installation; and there is aproblem which cannot centrifuge a sample according to various high-speedrotation conditions.

DISCLOSURE OF INVENTION Technical Problem

The present invention aims to solve these problems of the prior art andto provide an automatic balancing centrifugal apparatus by fluidcompensation, which compensates a load unbalance among buckets holdingsamples by injecting a fluid into the buckets or sucking the fluid fromthe buckets, thereby simplifying the overall structure of thecentrifugal apparatus, increasing the durability, and centrifuging alarge quantity of samples under various high-speed rotation conditionssmoothly.

Technical Solution

In order to achieve the above object, an automatic balancing centrifugalapparatus by fluid compensation according to the present inventioncomprises:

(a) rotors on which plural buckets are mounted;

(b) a centrifuge motor for rotating said rotors;

(c) a load measurement mechanism, which is installed so as to lift andlower along the rotation trace of said buckets;

(d) a position sensing mechanism for sensing whether or not each of saidbuckets is positioned right above said load measurement mechanism;

(e) a fluid compensation mechanism for injecting a fluid into saidbuckets or sucking the fluid from said buckets; and

(f) a main control part for controlling the overall operations of eachof said elements and controlling said fluid compensation mechanism sothat the loads of said buckets can be equal to each other.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a conventional automaticbalancing centrifugal apparatus.

FIG. 2 is a schematic perspective view of an automatic balancingcentrifugal apparatus by fluid compensation according to the presentinvention.

FIG. 3 is a schematic sectional view of a fluid compensation mechanismtaken along line A-A of FIG. 2.

FIG. 4 is an electric block diagram of an automatic balancingcentrifugal apparatus by fluid compensation according to the presentinvention.

DESCRIPTION OF THE MAIN REFERENCE NUMBER IN THE DRAWINGS

-   -   100 centrifugal apparatus    -   112 centrifuge motor    -   102 motor shaft    -   110 motor top plate    -   111 bucket positioning sensor    -   112 rotational speed sensor    -   113 slit disc    -   120 rotor    -   130 load measurement mechanism    -   131 vertical support    -   132 elevation motor    -   133 loading plate    -   134 photocoupler    -   135 position indicating marker    -   136 linear motion guide    -   140 bucket    -   141 sample holding plate    -   141A sample holding hole    -   142 sample cylinder    -   150 fluid compensation mechanism base    -   160 fluid storage tank    -   161 fluid feeding inlet    -   162 fluid sucking hole    -   163 fluid exhaust outlet    -   171 exhaust pump    -   172 sucking pump    -   173 connection tube    -   174 nozzle    -   180 elevation motor    -   182 nozzle support    -   183 elevation plate    -   184 slide center    -   185 linear bush    -   186 linear motion guide    -   187 screw shaft    -   188 position indicating marker    -   188U upper limit indicating slit    -   188L lower limit indicating slit    -   189 photocoupler    -   200 main control part    -   202 key input part    -   204 speed sensing part    -   206 bucket positioning sensing part    -   208 indicating part    -   210 centrifuge motor drive part    -   212 centrifuge motor    -   220 load measurement part    -   222 position sensing part    -   224 load sensor    -   226 elevation motor drive part    -   228 elevation motor    -   230 fluid compensation part    -   232 position sensing part    -   233 elevation motor    -   234 elevation motor drive part    -   236 pump drive part    -   238 pump

MODE FOR THE INVENTION

Hereinafter, an automatic balancing centrifugal apparatus by fluidcompensation according to preferred embodiments of the present inventionwill be explained in detail with reference to the accompanying drawings.

FIG. 2 is a perspective view showing a schematic constitution of anautomatic balancing centrifugal apparatus by fluid compensationaccording to the present invention. FIG. 3 is a schematic sectional viewof a fluid compensation mechanism taken along line A-A of FIG. 2. Asshown in FIGS. 2 and 3, the centrifugal apparatus by fluid compensationof the present invention may comprise: rotors (120) on which a pluralityof buckets (140) are mounted; a centrifuge motor (101) for rotating saidrotors (120); a load measurement mechanism (130) which is fixed in agiven place and measures the loads of the buckets (140) in apredetermined order; a position sensing mechanism for sensing whether ornot the buckets (140) are positioned at a predetermined stationaryposition, that is, right above the load measurement mechanism (130); anda fluid compensation mechanism which is fixed at a space above thebuckets (140) and which injects a fluid into the buckets (140) or sucksthe injected fluid from the buckets (140).

In the above-described constitution, the rotors (120) are axiallyconnected at the center thereof with the motor shaft (102), and maycomprise either even or odd numbers of rotor arms supporting the buckets(140). However, in either case, each of the rotor arms is preferablyformed so as to have the same length from the center of the motor shaftand to be conformal to each other. Reference numeral 110 represents atop plate of the centrifuge motor on which the various necessarycomponents are mounted.

The load measurement mechanism (130) may be embodied as an elevator-typeload measurement mechanism as described above, and the loading plate(133) may be installed so as to be positioned right below the rotationtrace of the buckets (140). The load measurement mechanism (130) maycomprise: an elevation motor (132) for lifting the loading plate (133)toward the buckets (140); a vertical support (131) for supporting theelevation motor (132) and remaining components; a slide center (notshown) which is fixed to the center portion of the loading plate (133)while being screwed to the screw rotation shaft (not shown) of theelevation motor (132) by a female screw formed at the center of theslide center; a linear motion guide (136) for guiding a linear motion ofthe loading plate (133); a load sensor (not shown) for measuring theload applied to the loading plate (133); a position indicating marker(135) on which slits (not shown) indicating the uppermost and lowermostpositions of the loading plate (133) are formed; and a photocoupler(134) which comprises a light emitting element and a photodetector,which are installed on opposite sides of a groove into which the distalend with slits of the position indicating marker (135) is interposed.

The position sensing mechanism may comprise a slit disc (113), which isaxially bonded with the motor shaft (102) and in which slits indicatingthe positioning of each of the buckets (140) are formed on thecircumference thereof in a radial direction, and a bucket positioningsensor (111) which comprises a photocoupler including a light emittingelement and a photodetector, which are installed on the opposite sidesof a groove into which the circumference of the slit disc (113) isinterposed. A plurality of slits for measuring velocity are formed onthe circumference of the slit disc (113) in a radial direction. Theposition sensing mechanism further includes a rotational speed sensor(112) comprising a photocoupler for sensing the velocity. In this case,positioning slits must be formed in at least the same number of that ofthe buckets (140), and velocity measurement slits are formed in morethan the number of the positioning slits. Preferably, the length of thepositioning slits is formed longer than that of the velocity measurementslits in order to differentiate both from each other.

The buckets (140) may be formed as a cylindrical body having a closedbottom surface, and a sample holding plate (141) for holding samplecylinders is mounted within the buckets (140). The sample cylinders(142) are inserted into a plurality of sample holding holes (141A) ofthe sample holding plate (141) to be supported, and a nozzle opening(not shown), through which a nozzle, as will be described below, entersand exits, is formed at the center of the sample holding plate (141).

The fluid compensation mechanism may comprise a base (150) on whichcomponents thereof are mounted; a fluid storage tank (160) which isfixed on the base (150) and in which a fluid is stored; a nozzle (174)which enters and exits said buckets to inject the fluid into the buckets(140) or suck the injected fluid from the buckets (140); a nozzlesupport (182) for supporting the nozzle (174) so as to be positioned atthe middle of the buckets (140); an elevation plate (183) which liftsand lowers while supporting the nozzle support (182); a linear motionguide (186) and a linear bush (185) for guiding an up-and-down motion ofthe elevation plate (183) smoothly; an elevation motor (180) which isfixed on the base (150); a screw shaft (187) which is axially connectedwith the elevation motor (180); a slide center (184) which is fixed atthe center of the elevation plate (183) and which is screwed with thescrew shaft (187) by a female screw formed on the inner circumferentialsurface thereof; a position indicating marker (188) on which slits(188U, 188L) indicating the uppermost and lowermost positions of themovement of the elevation plate (183); a photocoupler (189) for theposition sensor which is fixed on the elevation plate (183) and whichcomprises a light emitting element and a photodetector, which areinstalled on opposite sides of a groove into which the distal end withslits of the position indicating marker (188) is interposed. The fluidstorage tank (160) has a fluid feeding inlet (161) in a given place, forexample, on the top surface thereof, a fluid exhaust outlet (163) on alower part of a side surface thereof, and a fluid sucking hole (162) onan upper part of the side surface thereof. In addition, the sucking hole(162) is connected to a sucking pump (172), and an exhaust pump (171) isconnected to the fluid exhaust outlet (163).

In the above-described constitution, the center of the loading plate(133) of the load measurement mechanism (130) and the nozzle (174) ofthe fluid compensation mechanism are preferably located on the samevertical line. A reflective photocoupler type, a magnetic detectiontype, that is, a magnet and reed switch type, a potentiometer type, or avariable resistor type, and the like may be adopted by substituting thephotocouplers for the slit disc (113) and the bucket positioning sensor(111) of the position measurement mechanism, and the photocouplers (134,189) for the position indicating markers (135, 188) for measuring thepositions which are installed respectively at the load measurementmechanism (130) and the fluid compensation mechanism. Furthermore,instead of using the exhaust pump (171) and the sucking pump (172), asingle reversible pump, which integrates the two pumps, may be used. Insuch case, the fluid sucking hole, the fluid exhaust outlet, theconnection tube, and the like can be integrated into one piece.Reference numeral “173” denotes the connection tube which connects theexhaust pump (171) and the sucking pump (172) to the nozzle (174).

FIG. 4 is an electrical block diagram of the automatic balancingcentrifugal apparatus by fluid compensation according to the presentinvention. For the sake of easier understanding, equivalent componentsin FIGS. 2 and 3 have been given different reference numerals. As shownin FIG. 4, the automatic balancing centrifugal apparatus by fluidcompensation may comprise a key input part (202) for inputting orselecting various functions required for the apparatus; a speed sensingpart (204) for sensing the rotational speed of the buckets (140); abucket position sensing part (206) for sensing the setup position of thebuckets (140); a display part (208) for displaying the input indicationor the operating state; a centrifuge motor (212) and a drive part (210)thereof; a load measurement part (220) that is an electricalconfiguration of the load measurement mechanism (130); a fluidcompensation part (230) that is an electrical configuration of the fluidcompensation mechanism; a main control part (200) for generallycontrolling each of the components.

In the above-described constitution, the centrifuge motor (210) mayadopt either an AC or DC motor having a speed control function and anelectrical braking function, or a servo motor capable of controlling thespeed and position. The speed sensing part (204) may comprise the speedsensor (112) and the peripheral circuit components thereof. The bucketpositioning sensing part (206) may comprise the bucket positioningsensor (111) and the peripheral circuit components thereof. The displaypart (208) may consist of typical LEDs for displaying numbers or statesor image displays such as CRTs or LCDs. The load measurement part (220)may comprise a position sensing part (222), which consists of thephotocoupler (134) and the peripheral circuit components thereof, and aload sensing part (224) for sensing the load applied to the loadingplate (133), and preferably, a piezoelectric sensor, an elevation motor(228) and the drive part (226) thereof. Likewise, the fluid compensationpart (230) may comprise the position sensing part (232), which consistsof the photocoupler (289) and the peripheral circuit components thereof,an elevation motor (234) and the drive part (233) thereof, the exhaustpump and the sucking pump (238) (or a reversible pump) and the drivepart (236) thereof.

Hereinafter, the operation of the automatic balancing centrifugalapparatus by fluid compensation according to the present invention willbe explained in detail for a case where four buckets are used, but notrestricted thereto.

Firstly, the centrifuge motor rotates to position a bucket (a) above theloading plate (133) of the load measurement mechanism (130) by a sensingsignal from the bucket positioning sensing part (206). The loading plate(133) of the load measurement mechanism (130) is raised up to the upperlimit by a sensing signal from the position sensing part (222), and theload of the buckets (140) is measured by the load measurement part (224)while the restraint of the buckets (140) is released from the rotor arm.After the measured load is stored in a data memory (not shown) embeddedin the main control part (200), the loading plate (133) is again lowereddown to the lower limit by a sensing signal from the position sensingpart (222). Subsequently, the centrifuge motor (212) rotates to positiona bucket (c), which is axially symmetric with the bucket (a), exactlyabove the loading plate (133) of the load measurement mechanism (130) bya sensing signal from the bucket positioning sensing part (206). Theload of the bucket (c) is measured in the same manner as the bucket (a)to be then stored in the data memory, and then the load differentialbetween the two buckets (a, c) is calculated.

After the load differential is calculated, the elevation plate (183),that is, the nozzle (174), is lowered by the elevation motor (234) whilethe bucket of a smaller load is put on the loading plate (133), and theexhaust pump (238) is activated to introduce a fluid into the bucket(140) at an amount equivalent to the load differential while the loadsensing part (224) senses the load of the bucket. The remaining twobuckets (b, d) are compensated for the load differential in the samemanner. Meanwhile, in a case where an odd number of buckets are used,after the load of each bucket is measured one after another, theremaining buckets are compensated a fluid equivalent to the loaddifferential based on the heaviest bucket.

If the loads of all the buckets are equal to each other, the centrifugemotor (212) rotates to perform centrifugation. After the centrifugationis completed, the sucking pump (238) is actuated to suck all the fluidinjected into each of the buckets (140) back to the fluid storage tank(160). Lastly, the centrifuged sample cylinders (142) are drawn out ofeach of the buckets (140), so the centrifugation processes areterminated.

The present invention is not limited to the embodiment disclosed but maybe varied and modified within the scope of the following claims.

INDUSTRIAL APPLICABILITY

As described above, the centrifugal apparatus of automatic balancingtype by fluid compensation of the present invention does not need a slipring since the rotor consists of a simple mechanism. Accordingly, theoverall configuration of the centrifugal apparatus is simplified and thedurability thereof is increased. Furthermore, since the structure of therotor becomes slim, the rotor can mount a large quantity of or aplurality of buckets, and thus a relatively large number of samples canbe processed at one centrifugation.

1. An automatic balancing centrifugal apparatus by fluid compensation,comprising: (a) rotors on which a plurality of buckets are mounted; (b)a centrifuge motor for rotating said rotors; (c) a load measurementmechanism, which is installed so as to lift and lower within therotation trace of said buckets; (d) a position sensing mechanism forsensing whether or not each of said buckets is positioned above saidload measurement mechanism; (e) a fluid compensation mechanism forinjecting a fluid into said buckets or sucking the fluid from thebuckets; and (f) a main control part for controlling the overalloperations of each of said elements and controlling said fluidcompensation mechanism so that the loads of said buckets can becomeequal to each other.
 2. The automatic balancing centrifugal apparatus byfluid compensation according to claim 1, wherein the arms of said rotorshave the same length from the center of a shaft and to be conformal toeach other.
 3. The automatic balancing centrifugal apparatus by fluidcompensation according to claim 1, wherein said load measurementmechanism comprises: (a) a loading plate to which the load of saidbuckets are applied; (b) an elevation motor for lifting or lowering saidloading plate toward said buckets (140); (c) a screw rotation shaftwhich is axially connected with said elevation motor; (d) an elevationshaft for supporting said loading plate with being screwed to said screwrotation shaft; (e) a linear motion guide means for guiding aup-and-down motion of the loading plate; (f) a load sensor for measuringthe load applied to the loading plate; and (g) position sensing meansfor sensing the uppermost and lowermost positions of the loading plate.4. The automatic balancing centrifugal apparatus by fluid compensationaccording to claim 1, wherein said fluid compensation mechanismcomprises: (a) a fluid storage tank in which a fluid is stored and afluid opening are formed in a given place; (b) a nozzle which injectsthe fluid into said buckets or sucks the fluid from said buckets; (c)pumping means which is connected to said fluid opening to exhaust thefluid to the nozzle or to suck the fluid from the nozzle; (d) aconnection tube for connecting said pumping means with said nozzle; (e)a nozzle support for supporting said nozzle so as to be positioned atthe middle of said buckets; (f) an elevation plate which elevates andlowers while supporting said nozzle support; (g) a linear motion guidemeans for guiding an up-and-down motion of said elevation platesmoothly; (h) an elevation motor which is fixed on a base; (i) a screwshaft which is axially connected with said elevation motor; (j) a slidecenter which is fixed at the center of said elevation plate and which isscrewed with said screw shaft; and (k) position sensing means forsensing the uppermost and lowermost positions of the movement of saidelevation plate (183).
 5. The automatic balancing centrifugal apparatusby fluid compensation according to claim 4, wherein said buckets areformed as a cylindrical body with the lower surface closed, a pluralityof sample holding holes for holding sample cylinders being formed withinsaid buckets and a nozzle opening, through which a nozzle enters andexits, being formed at the center of said buckets.
 6. The automaticbalancing centrifugal apparatus by fluid compensation according to claim5, wherein said pumping means is a single reversible pump capable ofsucking and exhausting the fluid.
 7. The automatic balancing centrifugalapparatus by fluid compensation according to claim 6, wherein the centerof said loading plate and said nozzle are located on the same verticalline.
 8. The automatic balancing centrifugal apparatus by fluidcompensation according to claim 1, wherein said position sensingmechanism comprises a slit disc, which is axially connected with themiddle of the motor shaft and in which slits indicating the positioningof each of the buckets are formed on the circumference thereof in aradial direction, and a bucket positioning sensor which comprises aphotocoupler including a light emitting element and a photodetector,which are installed on the opposite sides of a groove into which thecircumference of the slit disc is interposed.
 9. The automatic balancingcentrifugal apparatus by fluid compensation according to claim 2,wherein said position sensing mechanism comprises a slit disc, which isaxially connected with the middle of the motor shaft and in which slitsindicating the positioning of each of the buckets are formed on thecircumference thereof in a radial direction, and a bucket positioningsensor which comprises a photocoupler including a light emitting elementand a photodetector, which are installed on the opposite sides of agroove into which the circumference of the slit disc is interposed. 10.The automatic balancing centrifugal apparatus by fluid compensationaccording to claim 3, wherein said position sensing mechanism comprisesa slit disc, which is axially connected with the middle of the motorshaft and in which slits indicating the positioning of each of thebuckets are formed on the circumference thereof in a radial direction,and a bucket positioning sensor which comprises a photocoupler includinga light emitting element and a photodetector, which are installed on theopposite sides of a groove into which the circumference of the slit discis interposed.
 11. The automatic balancing centrifugal apparatus byfluid compensation according to claim 4, wherein said position sensingmechanism comprises a slit disc, which is axially connected with themiddle of the motor shaft and in which slits indicating the positioningof each of the buckets are formed on the circumference thereof in aradial direction, and a bucket positioning sensor which comprises aphotocoupler including a light emitting element and a photodetector,which are installed on the opposite sides of a groove into which thecircumference of the slit disc is interposed.
 12. The automaticbalancing centrifugal apparatus by fluid compensation according to claim5, wherein said position sensing mechanism comprises a slit disc, whichis axially connected with the middle of the motor shaft and in whichslits indicating the positioning of each of the buckets are formed onthe circumference thereof in a radial direction, and a bucketpositioning sensor which comprises a photocoupler including a lightemitting element and a photodetector, which are installed on theopposite sides of a groove into which the circumference of the slit discis interposed.
 13. The automatic balancing centrifugal apparatus byfluid compensation according to claim 6, wherein said position sensingmechanism comprises a slit disc, which is axially connected with themiddle of the motor shaft and in which slits indicating the positioningof each of the buckets are formed on the circumference thereof in aradial direction, and a bucket positioning sensor which comprises aphotocoupler including a light emitting element and a photodetector,which are installed on the opposite sides of a groove into which thecircumference of the slit disc is interposed.
 14. The automaticbalancing centrifugal apparatus by fluid compensation according to claim7, wherein said position sensing mechanism comprises a slit disc, whichis axially connected with the middle of the motor shaft and in whichslits indicating the positioning of each of the buckets are formed onthe circumference thereof in a radial direction, and a bucketpositioning sensor which comprises a photocoupler including a lightemitting element and a photodetector, which are installed on theopposite sides of a groove into which the circumference of the slit discis interposed.
 15. The automatic balancing centrifugal apparatus byfluid compensation according to claim 8, wherein a plurality of slitsfor measuring the rotational speed of said buckets are formed on thecircumference of said slit disc in a radial direction; said apparatusfurther includes a photocoupler for measuring the velocity, whichcomprises a light emitting element and a photodetector, which areinstalled on opposite sides of a groove into which the circumference ofsaid slit disc is interposed; and said main control part controls therotational speed of said centrifuge motor based on a sensing signal fromsaid photocoupler.
 16. The automatic balancing centrifugal apparatus byfluid compensation according to claim 9, wherein a plurality of slitsfor measuring the rotational speed of said buckets are formed on thecircumference of said slit disc in a radial direction; said apparatusfurther includes a photocoupler for measuring the velocity, whichcomprises a light emitting element and a photodetector, which areinstalled on opposite sides of a groove into which the circumference ofsaid slit disc is interposed; and said main control part controls therotational speed of said centrifuge motor based on a sensing signal fromsaid photocoupler.
 17. The automatic balancing centrifugal apparatus byfluid compensation according to claim 10, wherein a plurality of slitsfor measuring the rotational speed of said buckets are formed on thecircumference of said slit disc in a radial direction; said apparatusfurther includes a photocoupler for measuring the velocity, whichcomprises a light emitting element and a photodetector, which areinstalled on opposite sides of a groove into which the circumference ofsaid slit disc is interposed; and said main control part controls therotational speed of said centrifuge motor based on a sensing signal fromsaid photocoupler.
 18. The automatic balancing centrifugal apparatus byfluid compensation according to claim 11, wherein a plurality of slitsfor measuring the rotational speed of said buckets are formed on thecircumference of said slit disc in a radial direction; said apparatusfurther includes a photocoupler for measuring the velocity, whichcomprises a light emitting element and a photodetector, which areinstalled on opposite sides of a groove into which the circumference ofsaid slit disc is interposed; and said main control part controls therotational speed of said centrifuge motor based on a sensing signal fromsaid photocoupler.
 19. The automatic balancing centrifugal apparatus byfluid compensation according to claim 12, wherein a plurality of slitsfor measuring the rotational speed of said buckets are formed on thecircumference of said slit disc in a radial direction; said apparatusfurther includes a photocoupler for measuring the velocity, whichcomprises a light emitting element and a photodetector, which areinstalled on opposite sides of a groove into which the circumference ofsaid slit disc is interposed; and said main control part controls therotational speed of said centrifuge motor based on a sensing signal fromsaid photocoupler.
 20. The automatic balancing centrifugal apparatus byfluid compensation according to claim 13, wherein a plurality of slitsfor measuring the rotational speed of said buckets are formed on thecircumference of said slit disc in a radial direction; said apparatusfurther includes a photocoupler for measuring the velocity, whichcomprises a light emitting element and a photodetector, which areinstalled on opposite sides of a groove into which the circumference ofsaid slit disc is interposed; and said main control part controls therotational speed of said centrifuge motor based on a sensing signal fromsaid photocoupler.
 21. The automatic balancing centrifugal apparatus byfluid compensation according to claim 14, wherein a plurality of slitsfor measuring the rotational speed of said buckets are formed on thecircumference of said slit disc in a radial direction; said apparatusfurther includes a photocoupler for measuring the velocity, whichcomprises a light emitting element and a photodetector, which areinstalled on opposite sides of a groove into which the circumference ofsaid slit disc is interposed; and said main control part controls therotational speed of said centrifuge motor based on a sensing signal fromsaid photocoupler.